(1) Field of the Invention
The present invention relates to a paper feeder built in an image forming apparatus such as a copier, printer, facsimile machine or the like. In particular, the present invention relates to an improvement of a paper feeder having a multiple number of paper feed cassettes arranged abreast at the same level.
(2) Description of the Prior Art
Conventionally, with concern to image forming apparatus such as copiers, printers facsimile machines and multifunctional machines consisting of these, there has been a demand of reducing the footprint of the apparatus to as small as possible. To meet this demand, so-called vertical feed type image forming apparatus have become widespread, in which paper is fed from the paper feed cassette arranged at the bottom of the image forming apparatus and conveyed along the paper feed path laid out vertically to the paper output tray located at the top.
Concerning the image forming apparatus of this type, there is also another demand for reducing the frequency of paper loading task by increasing the capacity of the stored amount of paper of sizes, which are frequently used (e.g., A4 size paper, etc.). To meet this demand, a paper feeder arrangement has been known as disclosed in Japanese Patent Application Laid-Open Hei 10 No. 194486, for example, in which a multiple number of paper feed cassettes of an identical size are arranged abreast at the same level.
Now, this paper feeder arrangement will be described. As shown in FIG. 1 (a side view showing an outline of the paper feeder arrangement), the paper feeder arrangement of this kind has a pair of paper feed cassettes a and b for paper of an identical size, arranged abreast at the same level. One paper feed cassette, designated at a, is located on the upstream side, the other paper feed cassette, designated at b, is located on the downstream side. A pickup roller c with a pair of feed rollers d is disposed on the paper delivery side of each of paper feed cassettes a and b. Formed over the downstream side paper feed cassette b is a paper delivery path f for delivering a sheet picked up from upstream side paper feed cassette a to paper feed path e. As one example of operation of this paper feed arrangement, upon image forming, sheets of paper are successively delivered first from the downstream side paper feed cassette b toward the image forming station, and when the paper in the downstream side paper feed cassette b is used up, the paper feed operation is shifted to the upstream side paper feed cassette a. In this way, the stored amount of paper of a size which is frequently used is increased so that the frequency of the paper loading task can be reduced.
In the paper feeder arrangement disclosed in the above publication, the upstream and downstream side paper cassettes g and h are adapted to be pulled out individually, as shown in FIGS. 2A to 2C while the paper pickup path, designated at j, formed over the downstream side paper feed cassette h and upstream side paper feed cassette g are adapted to be pulled out integrally (see FIGS. 2B and 2C). In actual practice, when paper needs to be supplied to the downstream side paper feed cassette h or when paper jamming of a sheet delivered from this downstream side paper feed cassette h has occurred, the downstream side paper feed cassette h should be drawn out. On the other hand, when paper needs to be supplied to the upstream side paper feed cassette g or when paper jamming of a sheet delivered from the upstream side paper feed cassette g has occurred, the upstream side paper feed cassette g should be drawn out.
However, in the above paper feeder arrangement, both the upstream and downstream side paper feed cassettes need to be supplied with paper, it is necessary to pull out each of the paper feed cassettes individually. Particularly, in the configuration where paper feed is taken over from one cassette to another when the paper in the first paper feed cassette has been used up, paper loading task is usually carried out at the same time for both the paper feed cassettes. Though there has been a demand for paper loading to be done at the same time for both the paper feed cassettes, each paper feed cassette has to be drawn out individually, so that the task of paper loading has been complicated and time-consuming.
The present invention has been devised in view of the above problems and it is therefore an object of the present invention to provide improvement in the operativity of paper loading in to each cassette of the paper feeder having multiple paper feed cassettes which are arranged abreast along the sheet feed direction at the same level.
In order to attain the above object, the present invention is configured so that the multiple paper feed cassettes arranged abreast are formed into a unibody structure and can be drawn out altogether from the image forming apparatus when they are pulled out.
In order to achieve the above object, the present invention is configured as follows:
In accordance with the first aspect of the present invention, a paper feeder which is provided for an image forming apparatus having image forming means for forming an image on a sheet and feeds sheets to the image forming means, the paper feeder includes: a multiple number of paper feed cassettes arranged abreast at approximately the same level in the sheet feed direction, the paper feed cassettes being formed into a unibody structure so that they can be pulled out altogether from the feeder body; and feed paths formed over the feed cassettes excepting the one located on the most upstream side with respect to the sheet feed direction, for conveying sheets supplied from the paper feed cassettes located on the upstream side of each cassette, and is characterized in that the feed path is adapted to make wider the gap thereof when the paper cassettes are pulled out, so as to allow a sheet stuck therein to be removed therefrom.
In accordance with the second aspect of the present invention, the paper feeder for use in an image forming apparatus having the above first feature is characterized in that the upper surfaces of the paper feed cassettes are arranged rising stepwise from the paper feed cassette located on the most downstream side toward the paper feed cassette located on the most upstream side with respect to the sheet feed direction.
In accordance with the third aspect of the present invention, the paper feeder for use in an image forming apparatus having the above first feature is characterized in that the feed path is formed by a pair of upper and lower guide plates and the lower guide plate is moved downwards so as to make wider the gap thereof.
In accordance with the fourth aspect of the present invention, the paper feeder for use in an image forming apparatus having the above third feature is characterized in that the level of the upper guide plate is set to be approximately equal to the upper edge of the cassette storage opening of the feeder body when the paper feed cassettes have been pulled out.
In accordance with the fifth aspect of the present invention, the paper feeder for use in an image forming apparatus having the above third feature is characterized in that the lower guide plate is pivotally supported at one end located on the interior side of the feeder body with respect to the direction of the paper feed cassettes being pulled out, and the gap of the paper feed path is made wider by rotating the lower guide plate downward about the pivot, and the rotational movement of the lower guide plate is achieved in linkage with the paper feed cassettes being pulled out from the feeder body and being pushed into the feeder body.
In accordance with the sixth aspect of the present invention, the paper feeder for use in an image forming apparatus having the above third feature is characterized in that when the paper feed cassettes have been pushed into the feeder body, the upper surface of the associated paper feed cassette abuts the underside of the lower guide plate so as to position the lower guide plate at a designated level that defines the feed path in cooperation with the upper guide plate.
In accordance with the seventh aspect of the present invention, the paper feeder for use in an image forming apparatus having the above sixth feature is characterized in that an abutment member that abuts the upper surface of the associated paper feed cassette is provided on the underside of the lower guide plate, and this abutment member has a surface inclined upward in the direction of the paper feed cassettes being pulled out when the lower guide plate is positioned at the designated level that forms the feed path in cooperation with the upper guide plate.
In accordance with the eighth aspect of the present invention, the paper feeder for use in an image forming apparatus having the above first feature is characterized in that each paper feed cassette has a pickup unit for picking up sheets from the paper feed cassette, and this pickup unit is comprised of a pickup roller for picking up one sheet from the paper feed cassette and a pair of feed rollers for delivering the sheet separated by the pickup roller to the image forming means.
In accordance with the ninth aspect of the present invention, the paper feeder for use in an image forming apparatus having the above eighth feature is characterized in that the pickup unit has bearing plates for supporting the pickup roller and paired feed rollers at their shaft ends in a rotatable manner.
In accordance with the tenth aspect of the present invention, the paper feeder for use in an image forming apparatus having the above eighth feature is characterized in that the pickup unit is able to pivot on an axis parallel to the axial direction of the pickup roller and paired feed rollers, so that the pickup unit can be moved between a first position where the pickup roller comes in contact with the sheet in the paper feed cassette and a second position where the pickup unit is removed from the top opening of the paper feed cassette.
In accordance with the eleventh aspect of the present invention, the paper feeder for use in an image forming apparatus having the above tenth feature is characterized in that the pickup unit is configured so as to rotate from the second position to the first position in linkage with the paper feed cassettes being pushed into the feeder body.
In accordance with the twelfth aspect of the present invention, the paper feeder for use in an image forming apparatus having the above eleventh feature is characterized in that the pickup unit has a projection that abuts a guide element formed on the feeder body and rotates the pickup unit from the second position to the first position when the paper feed cassettes are inserted into the feeder body.
In accordance with the thirteenth aspect of the present invention, the paper feeder for use in an image forming apparatus having the above twelfth feature is characterized in that the guide element has a surface inclined downward toward the side to which the paper feed cassette is pushed in, and the pickup unit is rotated from the second position to the first position whilst the projection is being guided by the inclined surface.
According to the configuration of the present invention, since paper feed cassettes are provided in a unibody structure, the paper feed cassettes can be pulled out altogether from the paper feeder body when sheets need to be supplied to each paper feed cassette. Therefore, it is possible to load sheets at the same time to all the paper feed cassettes in this pulled out position. Since feed paths of sheets delivered from paper feed cassettes located upstream are formed over the paper feed cassettes located downstream by making the upper level of each paper feed cassette different from others, the feed path can be formed straightly and approximately horizontally from the sheet pickup position of the paper feed cassette, which leads to smooth pickup of sheets from the paper feed cassette.
The invention is configured so that when a sheet has stuck in the feed path (when paper jam has occurred), the sheet can be readily removed. That is, the gap of the feed path can become wider upon removal of a sheet when paper jam has occurred in the feed path. Therefore it is possible for an operator to readily remove the sheet which has stuck therein.
According to the present invention, it is possible to spread the gap of the feed path with a relatively simple configuration.
According to the present invention, since the lower guide plate can also be positioned as high as possible, it is possible to secure a large enough margin for the lower guide plate to move down. More explicitly, it is possible to take a large enough space to remove the sheet being stuck in the feed path, which provides easier sheet removal.
Further, according to the present invention, since the device for actuating the lower guide plate to move vertically is so configured that the front side of the lower guide plate moves downwards so as to make wider the gap between the upper and lower guide plates when the paper feed cassettes are simply pulled out from the feeder body. That is, the feed path can be spread open to the user who pulls out the paper feed cassettes. In this way, since the gap between the guide plates can become wider when the paper feed cassettes have been pulled out, no special actuation for shifting the lower guide plate downward is needed, hence this provides beneficial operativity. Further, the lower guide plate returns to the original position in linkage with the insertion of the paper feed cassettes.
According to the present invention, a simple operation of pushing the paper feed cassettes into the feeder body causes the lower guide plate to return to its original position so that it creates the designated feed path in cooperation with the upper guide plate. Therefore, after the paper feed cassettes are pulled out in order to cancel paper jamming, this feature makes it possible for the image forming apparatus to smoothly recover its function after cancellation of paper jamming.
In the present invention, the guide mechanism for shifting the lower guide plate is configured so that when the paper feed cassette begins to be pulled out, the lower guide plate gradually moves down whilst the inclined surface of the abutment member is sliding over the upper surface of the paper feed cassette. When the paper feed cassette is fully drawn out, the lower guide plate has moved down to the lowest position. In contrast, when the paper feed cassette is pushed in, the lower guide plate gradually moves up whilst the inclined surface of the abutment member is sliding over the upper surface of the paper feed cassette, in the reverse order when the cassette is pulled out. When the paper feed cassette is pushed in completely, the lower guide plate is positioned at the predetermined feed path forming level that creates the feed path in cooperation with the upper guide plate.
In the present invention, the arrangement for picking up sheets from the paper feed cassettes is configured so that all the pickup units are pulled out integrally with the paper feed cassettes when paper feed cassettes are pulled out from the feeder body. Therefore, when paper jam has occurred at the pickup roller or at the paired feed rollers, the jammed sheet can be markedly easily removed from the image forming apparatus by drawing out the paper feed cassette.
According to the configuration of the present invention, if the pickup roller needs to be put into contact with the stack of sheets held in the paper feed cassette with a predetermined pressure applied thereto, it is possible to apply the necessary contact force of the pickup roller onto the sheet by exerting an appropriate urging force on the bearing plate. Thus, a relatively simple configuration makes it possible to adapt the pickup roller to produce a desired contact force.
According to the present invention, when sheets are loaded into the paper feed cassettes, the pickup rollers can be removed from the top openings of the paper feed cassettes by rotating the pickup units to their second positions. Therefore, this movement enlarges the open area of the top opening, thus enabling easy sheet loading.
According to the arrangement for returning the rotated pickup unit to its original position, the pickup unit can be returned to its original position (the first position) by mere insertion of the paper feed cassettes into the feeder body. Therefore, it is possible for the image forming apparatus to smoothly recover its function after paper loading.
Furthermore, according to the present invention, the pickup unit which has been rotated at the second position can be returned by rotating to the first position by abutment of the projection of the pickup unit against the guide element whilst the paper feed cassettes are being inserted into the feeder body.
Therefore, when the pickup unit returns to the first position, it is possible to reduce the impacts when this pickup unit interferes with other components, hence it is possible to prevent the pickup unit from being broken and reduce the impact sound. Further, the rotational speed of the pickup unit can be made relatively slow, so that noise accompanying the rotation can be inhibited.